Relay charge with a fuse of weakened explosive power

ABSTRACT

A RELAY CHARGE FOR USE WITH FUSES IN THE INITIATION OF INSENSITIVE EXPLOSIVES WHICH COMPRISES TWO PARTS PREFERABLY DETACHABLY CONNECTED WITH EACH OTHER, ONE OF THE TWO PARTS CONTAINS SECNDARY EXPLOSIVES WITHIN A STRUCTURALLY RIGID CASE, OPEN AT ONE END WHILE THE OTHER PART FORMS A DELAY ELEMENT WHICH IS CONNECTED WITH THE OPEN END OF THE CASE AND SERVES FOR THE ACCOMMODATION OF THE FUSE AND OF THE DELAY CHARGE. THE DELAY ELEMENT INCLUDES A SHOCK-SENSITIVE PRIMER COMPOSITION, A DELAY CHARGE AND A BASE CHARGE, APPROPRIATELY ENCAPSULED WITHIN A CASING.

United States Patent inventor Josef Prior Trolsdorf, Germany Appl. No.749,879 Filed Aug. 2, I968 Patented June 28, I971 Assignee Dyncmit NobelAktiengesellschalt 'l'roisdorl, Germany Priority Aug. 2, 1967 Germany063,738

RELAY CHARGE WITH A FUSE 0F WEAKENED EXPLOSIV E POWER 10 Claims, 1Drawing Fig.

US. Cl. 102/27, 7 102/29, 102/70 Int. Cl. F421) 3/10 Field 01 Search102/27- [56] References Cited UNITED STATES PATENTS 1,599,078 9/1926Corrie 102/29 2,441,248 5/1948 Morris et al. l02/86.5 2,771,033 11/1956Lewis et al.... 102/28 2,857,845 10/1958 Seovy 102/27 3,106,892 10/1963Miller.... 102/27 3,150,020 9/1964 Kilmer 149/37 Primary Examiner-VerlinR. Pendegrass Attorney-Craig and Antonelli ABSTRACT: A relay charge foruse with fuses in the initiation of insensitive explosives whichcomprises two parts preferably detachably connected with each other; oneof the two parts contains secondary explosives within a structurallyrigid case, open at one end while the other part forms a delay elementwhich is connected with the open end of the case and serves for theaccommodation of the fuse and of the delay charge. The delay elementincludes a shock-sensitive primer composition, a delay charge and a basecharge, appropriately encapsuled within a casing.

PATENTEI] JUN28 ram INVENTOR JOSEF PRIOR ATTORNEYS RELAY CHARGE WITH AFUSE F WEAKENED EXPLOSIVE POWER The present invention relates to a relayor magazine charge, and more particularly to a relay or primer chargewhich can be used in vertical blast-holes.

For the purpose of igniting explosives which are difiicult to set off orinitiate, for example, such as ammonium nitrate/Diesel oil," alsoreferred to as "nitrocarbonitrates, from the maximum depth of ablast-hole, fuses are employed which are incapable by themselves ofinitiating or setting off the main charge, i.e., without the means ofbooster charges or priming cartridges. It is required of these boostercharges that they can be initiated or set ofl by the fuse eitherinstantaneously or with a delay. However, on the other hand, theycannotbe excessively sensitive to shocks and impacts since they are installedat the deepest place of the blast-holes, which are vertical for the mostpart, and must be able to withstand, without being destroyed, the weightof the freely falling main charge placed or installed over the same.Consequently, demands have even been made occasionally that thesecharges not contain any initiating explosive. In any event, allsensitive parts are to be encapsulated in such a manner that no increasein danger is to be expected from this kind of. blasting.

Accordingly, it is the aim of this invention to provide a relay chargeby means of which the aforementioned requirements are fulfilled.According to the invention, the primer or relay charge essentiallyconsists of the priming cartridge, properly speaking, which isconstituted by a metallic container filled with explosives and ofsufiicient strength to withstand with certainty the pressure of theexplosive column resting thereon, and of the delay part. 7

As the explosive filling for the priming cartridge there may be usedconventional secondary explosives or explosive mixtures, such ascyclonite (RDX, hexogen) or pentaerythritol tetranitrate (PETN),dipentahexanitrate, nitromannite (mannitol hexanitrate), nitroglycerin,and nitroglycol explosives.

The delay part essentially consists of an external sleeve or casing,open on both sides, which encompasses a capsule having a strong-walledbottom in such a manner that an empty or hollow space is produced at oneend this outer casing and that the end of the fuse can be introducedinto this empty or hollow space and can be tightly clamped therein. Thecapsule with the strong-walled bottom contains, adjoining the bottom, a

shock-sensitive primer or detonator composition, for example, in theform of a percussion cap, a small empty tube retaining this compositionor percussion cap, a delay body or delay element, charged witha delaycomposition, a firing charge in this delay element, and finally a powdertrain charge. After completion of the charge, the capsule is sealed offin a watertight manner by means of a metallic or plastic foil, or bymeans of an impregnated paper foil.

The delay element and the relay or primer charge, properly speaking, areconnected with each other, at the latest shortly before use, with theaid of appropriate, conventional means, for instance, by means of athreaded part or an adapter with a bayonet-type connection.

Accordingly, it is an object of the present invention to provide aprimer and relay charge of the type described above which avoids bysimple means the aforementioned shortcomings and drawbacks encounteredin the prior art.

Another object of the present invention resides in a primer and relaycharge which increases the safety of operation, especially when used invertical blast-holes.

A further object of the present invention resides in a relay charge ofthe type described above which is able to withstand the explosivecharge, properly speaking, that rests on the same, and at the same timeminimizes the danger of excessive sensitivity to shocks and impacts. 7

These and further objects, features and advantages of the presentinvention will become more obvious from the following description, whentaken in conjunction with the accompanying drawing, which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

The single F IGURE is an axial cross-sectional view through oneembodiment of a relaycharge in accordance with the present invention.

Referring now to the single FIGURE of the drawing, the startingdetonation of the fuse l of any known, conventional construction actsthrough the reinforced bottom 2' of the internal capsule 2, on theshock-sensitive primer charge 3; the latter produces a flame whichignites the delay charge 5 across the empty tube 4. The delay charge 5burns up and ignites the firing charge 6 which, depending on the flamesensitivity of the powder charge, may be made of an especially stronglyflame-spraying firing charge. The firing charge 6 ignites the basecharge 7, and owing to the secure connection'8 of the delay element withthe relay charge 9, the latter is detonated.

Depending upon the explosive force of the fuse, it may be necessary toprovide on the bottom of the internal capsule 2, an additional boostercharge 10, for example, in the form of a primer or percussion cap, whichis directed toward the end of the fuse 1 and which increases a possiblyinadequate percussion of the fuse.

The shock-sensitive primer charge 3 and/or 10 may consist of aconventional mixture of potassium chlorate and of an explosive from theclass of the solid nitric acid esters, such as penthrite (PETN,pentaerythritol tetranitrate), nitromannite, or nitrostarch (starchnitrate), or also of any desired, known primer cap composition.

The delay charge 5 may consist, depending on the desired period ofdelay, of conventional thermite (Thermit )mixtures, e.g.,minimum/silicon; minium/boron;, potassium permanganate/antimony, and thelike. Depending upon the type of delay charge 5 and of the compositionof the base charge 7, it may be necessary to employ a firing charge 6for the ignition of a compressible base powder charge, for example, of amixture of minium/silicon, nitrocellulose or black powder, which firingcharge 6 is made of a flame-spraying thermite composition, such as, forexample, zirconium/minium.

Suitable charges 9 for the primer cartridge, properly speaking, areexplosives which are more sensitive with. respect to initiation thantetryl, i.e., cyclonite, penthrite, and other solid nitric acid esters,but also plastic mixtures on the basis of nitroglycerin or nitroglycol.

While 1 have shown and described only one embodiment in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to a person skilled in the art, and I therefore do not wish to belimited to the details as shown and described herein.

I claim:

1. A relay charge for delayed blasting operations initiated by means ofa fuse for detonating explosives from the bottom of a blast holecomprising a unilaterally closed structurally rigid case filled with asecondary explosive and delay means including a delay charge detachablyconnected between said rigid case and said fuse, said delay means beingprovided as an open cylindrical casing including a capsule having oneend open and the other end closed by a thickened bottom wall, ashock-sensitive primer cap positioned on the inner bottom wall of saidcapsule, said delay charge being spaced from said primer cap to form adelay space therebetween, a flameproducing composition in contact withsaid delay charge at the open end of said capsule, and a base chargepositioned ad jacent said flame-producing composition at the other endof said casing detachably connected to, said rigid case and spaced fromsaid secondary explosive, the other end of said casing including abayonet-type connection for receiving and holding said fuse.

2. A relay charge according to claim 1, wherein said delay means isconnected to said rigid case by a threaded connectron.

3. A relay charge according to claim 1, wherein said secondary explosiveis penthrite.

4. A relay charge according to claim 1, wherein a booster charge islocated outside said closed end of said capsule in said groupessentially consisting of minium, silicon, and nitrocellulose.

8. A relay charge according to claim 7, wherein said flameproducingcharge consists of a mixture of materials selected from the groupconsisting of zirconium and minium.

9. A relay charge according to claim 8, wherein the delay chargeconsists of a mixture of minium and silicon.

10. A relay charge according to claim 9, wherein said secondaryexplosive is penthrite.

